To lose 3kg in 2 weeks which is essentially 1.5kg in 1 week is not exactly a realistic amount of weight loss to expect unless you were clinically obese.
You should be aiming for 2lb/week (.9kg/week).
Simply eat less and exercise more.
Focus on taking in mostly veggies/fruits/lean meats and minimize or cut out all processed foods from your diet.
This will make it that much easier for you to lose weight as these types of foods are more satiating and also lower in calories.
To make it simple....If you're not losing weight, eat less at each meal..
If that is still not doing the trick after a few days, add more cardio or increase the duration/intensity of the cardio.
There's a lot more info on how to successfully accomplish this here.